In cracking operations, (pyrolysis) such as in the cracking of ethane, propane and naphthas to olefins, oxygenated compounds, including carbonyl compounds, are formed. The amount of carbonyl compounds, such as aldehydes and ketones, formed in such an operation can vary widely, but is typically 1-100 ppm in the gas stream with concentrations as high as 1000 ppm occasionally being encountered. The carbonyl level is dependent on the type of feedstock used and cracking temperatures. When the gas stream is passed through a basic wash (pH&gt;7) to remove acidic components such as hydrogen sulfide and carbon dioxide, oxygenated compounds and carbonyl compounds are also removed. These oxygen compounds, particularly acetaldehyde, will undergo polymerization in the presence of the base.
In the wash tower, the polymer will settle on the trays resulting in a loss of heat transfer efficiency, necessitating a costly shutting down of the unit in order to clean the trays. The type of basic wash systems where treatment is required to inhibit fouling include amine acid gas scrubber (e.g., MEA, DEA, isopropyl amine, butyl amine, etc.) and caustic wash systems.